Portable terminals such as mobile terminals (i.e., cellular phones), electronic schedulers, and personal complex terminals have become an important aspect of current society. In essence, these portable terminals have developed into important means of information transmission.
Almost all portable terminals use a battery as a power source. The battery is typically charged using a charger that is connected to the portable terminal.
The portable terminal may include certain components for measuring the remaining capacity of the battery and may monitor the remaining capacity information of the battery while the battery is being charged. Recently, portable terminals have been miniaturized by integrating discrete components, thus reducing the number of components. Also, the components for measuring the remaining capacity of the battery have also been miniaturized.
A portable terminal which does not include components for measuring the remaining capacity of the battery may monitor the remaining capacity of the battery by measuring a voltage of the battery while the battery is charged and loading the remaining capacity of the battery, which corresponds to the measured voltage. In general, the charger performs a Constant Current (CC) charging mode and a Constant Voltage (CV) charging mode when charging the battery.
FIG. 1 is a graph illustrating voltage of a battery and the remaining capacity of the battery based on a charging curve of the battery.
Referring to FIG. 1, while a battery charge is in progress for a CC charging mode of charging the battery with a CC (500 mA), a voltage of the battery increases. If the voltage of the battery arrives at a fully charged voltage of 4.2 volts (V), the charger changes to a CV charging mode of charging the battery with a constant voltage of 4.2V. When a charging current to the battery reduces to a sufficiently small amount of current while the CV charging mode is performed, the charging of the battery is completed.
As described above, although the battery may have a full charged voltage while being charged in the CC mode, it should also be charged using the CV charging mode to be fully charged. However, when the voltage of the battery arrives at a full charged voltage while the battery is charged, a conventional portable terminal may display the remaining capacity of the battery as being fully charged. Thus, a problem may exist where the conventional portable terminal does not provide the accurate remaining capacity of the battery.